Does/should Linux Mint adhere to the "FreeBSD File Formats Manual" when it comes to the passwd file?
If you choose to install Linux Mint using a name that includes an ampersand, you'll be surprised at the results. (at least, I was) In many cases where the user's name is being displayed, the ampersand is replaced by a capitalized version of the user's login name.
In Xfce, Whisker Menu does this. In MATE, both the locked screen dialog and the Configuration Center's "About me" does this. However, "Users and Groups" does not replace the ampersand.
I found that this behavior is due to glib's g_get_real_name which implements the following passage from man passwd in "FreeBSD File Formats Manual". http://www.manpages.info/freebsd/passwd.5.html
If an ampersand (`&') character appears
within the fullname field, programs that use this field will substitute
it with a capitalized version of the account's login name.
I found this to be confusing as a new user and would suggest warning the user about the use of '&' (or even disallowing its use). At least make it consistent throughout Linux Mint.